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  • 1
    ISSN: 1438-8359
    Schlagwort(e): Organ blood flow ; Carbonic anhydrase ; Carbonic anhydrase inhibitor ; Acetazolamide ; Laser flowmeter
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Purpose We investigated the mechanism by which inhibition of carbonic anhydrase (CA) increases organ blood flow. Methods Regional blood flow (rBF) in white rabbits anesthetized with ketamine/urethane was measured in the kidney, liver, stomach wall, and abdominal muscle by means of laser blood flow probes. Data obtained from rabbits receiving acetazolamide (AZ) to inhibit CA were compared with those obtained from rabbits ventilated with air containing increased concentrations of CO2. Results Systolic blood pressure, body temperature, hemoglobin, and base excess were unaffected by either treatment. Inhalation of CO2 increased blood flow in all organs tested as well as the cardiac output and PCO2 but decreased pH. Inhibition of CA by AZ administration increased the rBF only in the liver and kidney and did not increase cardiac output or decrease pH. Conclusion Administration of AZ increased rBF in the tissues and organs that contained large amounts of CA without increasing the cardiac output or decreasing the pH, which suggests a direct local effect. A differential sensitivity to the retention of CO2 is suggested as a possible mechanism of the selectivity of the increase in rBF.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1438-8359
    Schlagwort(e): Inhalation anesthetics ; Artemia salina ; Motility ; Video monitoring ; Cooperativity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The swimming movement of artemia salina in the artificial sea water was measured by using the video camera system in the absence and presence of anesthetics, i.e. enflurane, halothane, and isoflurane. The movement of artemia looked random at a glance but the obtained distribution curve for the swimming speed was skewed toward the high speed side somewhat resembling a Maxwellian distribution curve seen in the statistics of ideal gases. When anesthetic were added, the distribution curve became sharpened and shifted to the low speed side, which is similar to a behavior of ideal gasses when they are cooled down. The mean swimming-speed was decreased eventually leading to an irreversible death with increasing the anesthetic dose. The activity was analyzed by using the hydrodynamic equation. The ED50, which is a dose that causes a 50% reduction in the activity, of all anesthetics used in this study was quite similar to the MAC values for human. It was also suggested that an interaction between anesthetics and artemia was highly cooperative since the larger Hill coefficients were obtained for all three anesthetics used. (Takasaki T, Tatara T, Suezaki Y, et al.: Effect of inhalation anesthetics on swimming activity of artemia salina. J Anesth 5: 287–293, 1991)
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1615-2573
    Schlagwort(e): Blood flow ; Microspheres ; Carbonic anhydrase ; Acetazolamide
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Inhibitors of carbonic anhydrase activity have been found to increase blood and organPCO2 and to increase blood flow (BF) in individual organs. To determine whether carbonic anhydrase inhibition coordinately induces an increase in BF in several organs, we assayed the effect of the carbonic anhydrase inhibitor, acetazolamide (AZ), on BF in rabbit organs using the colored microsphere (CM) assay. Eight female white rabbits were anesthetized with ketamine and urethane, and administered three sequential doses of 4 mg/kg AZ. After each dose, the rabbits were injected with 9 × 105 CMs of different colors, and arterial blood was collected. We found that AZ had no effect on blood pressure, body temperature, hemoglobin conentration, orPaCO2. In contrast, 12 mg/kg AZ significantly increasedPaO2 and significantly decreased base excess. When we measured organ BF, we observed, in response to 12 mg/kg AZ, an 82% increase in brain BF and a 55% increase in kidney BF, but no change in BF of the liver, stomach wall, or abdominal muscle. These findings suggest that the inhibition of carbonic anhydrase activity by AZ, which decreases the rate of CO2 conversion to HCO 3 - , causes the retention of CO2 in tissues and organs, and thus increases BF in specific organs. Administration of carbonic anhydrase inhibitors, such as AZ, may increase BF to the brain and kidney without reducingPaO2, thereby increasing the supply of oxygen in conditions involving hypoxia such as ischemia and shock.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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